Il'ichev Pacific Oceanological Institute, Far Eastern Branch, Russian Academy of Sciences, 690041 Vladivostok, Russia.
Int J Mol Sci. 2024 May 24;25(11):5740. doi: 10.3390/ijms25115740.
Micro-sized particles of synthetic polymers (microplastics) are found in all parts of marine ecosystems. This fact requires intensive study of the degree of danger of such particles to the life activity of hydrobionts and needs additional research. It is evident that hydrobionts in the marine environment are exposed to microplastics modified by biotic and abiotic degradation. To assess the toxic potential of aging microplastic, comparative studies were conducted on the response of cytochemical and genotoxic markers in hemocytes of the mussel (Gould, 1850) after exposure to pristine and photodegraded (UV irradiation) polystyrene microparticles (µPS). The results of cytochemical tests showed that UV-irradiated µPS strongly reduced metabolism and destabilized lysosome membranes compared to pristine µPS. Using a Comet assay, it was shown that the nuclear DNA of mussel hemocytes showed high sensitivity to exposure to both types of plastics. However, the level of DNA damage was significantly higher in mussels exposed to aging µPS. It is suggested that the mechanism of increased toxicity of photo-oxidized µPS is based on free-radical reactions induced by the UV irradiation of polymers. The risks of toxic effects will be determined by the level of physicochemical degradation of the polymer, which can significantly affect the mechanisms of toxicity.
微尺寸的合成聚合物颗粒（微塑料）在海洋生态系统的各个部分都有发现。这一事实需要深入研究这些颗粒对水生生物生命活动的危险程度，并需要进一步研究。显然，海洋环境中的水生生物会接触到被生物和非生物降解作用修饰的微塑料。为了评估老化微塑料的毒性潜力，我们对贻贝（Gould，1850）血细胞中的细胞化学和遗传毒性标记物在暴露于原始和光降解（UV 照射）聚苯乙烯微颗粒（µPS）后的反应进行了比较研究。细胞化学测试的结果表明，与原始µPS 相比，UV 照射的µPS 强烈降低了代谢并破坏了溶酶体膜。使用彗星试验表明，贻贝血细胞的核 DNA 对两种类型的塑料暴露均表现出高度敏感性。然而，暴露于老化µPS 的贻贝中的 DNA 损伤水平明显更高。据推测，光氧化µPS 毒性增加的机制基于聚合物的 UV 照射诱导的自由基反应。毒性影响的风险将取决于聚合物的物理化学降解程度，这会显著影响毒性机制。
